title: Augmentation of Achilles tendon repair with extracellular matrix xenograft: a biomechanical analysis.
abstract: BACKGROUND
  Achilles tendon rupture is a frequent injury in athletes and the general public. Cases of chronic rupture or poor tendon quality secondary to tendinopathy are challenging to repair primarily. Commercially available extracellular matrix materials have been utilized in recent years to augment tendon repair.
  
  
  OBJECTIVE
  Augmentation of Achilles tendon with extracellular matrix xenograft results in reduced repair site gapping and increased peak failure load in a cadaveric model featuring simulated physiologic loads.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten matched pairs of fresh-frozen human lower extremities amputated just below the knee were obtained and each Achilles tendon was sharply tenotomized. One randomly selected specimen from each matched pair underwent Achilles repair using a 4-strand Krackow technique with extracellular matrix xenograft augmentation (TissueMend Soft Tissue Repair Matrix), while the opposite tendon underwent suture repair alone as a control. Each tendon was then subjected to 1000 sinusoidal tensile loading cycles to 86 N during which repair site gapping was monitored, followed by distraction to failure. One pair was used to evaluate the effects of graft orientation and not included in the analysis.
  
  
  RESULTS
  Significantly less gapping was noted in the augmented tendon group at all time points after the 10th load cycle (P < .05). The mean repair site gapping after 1000 cycles of loading was 4.0 mm (range, 3.1-5.0 mm) in the augmented group and 6.5 mm (range, 4.1-8.6 mm) in the suture-only group. The ultimate failure load was 821 N (range, 613-1021 N) in the augmented group and 392 N (range, 322-481 N) in the suture-only group (P < .01).
  
  
  CONCLUSIONS
  The augmentation of Achilles tendon repair with extracellular matrix xenograft decreases gapping and increases load to failure immediately after surgery in a cadaveric model.
  
  
  CONCLUSIONS
  Tendon repair augmentation may allow more aggressive early rehabilitation, particularly in cases of chronic rupture or poor tendon quality. Further work is necessary to define indications for extracellular matrix graft augmentation of tendon repairs.
authors.affiliation: Duke Sports Medicine, Durham, North Carolina, USA. robert.magnussen@gmail.com
authors.forename: Robert A
authors.initials: RA
authors.lastname: Magnussen
authors.forename: Richard R
authors.initials: RR
authors.lastname: Glisson
authors.forename: Claude T
authors.initials: CT
authors.lastname: Moorman
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000473:pathology / Q000601:surgery*; D000328:Adult; D001696:Biomechanical Phenomena; D002102:Cadaver; D005109:Extracellular Matrix / Q000637:transplantation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012421:Rupture / Q000601:surgery; D013718:Tensile Strength; D055815:Young Adult